SACRAMENTO, Calif. — California lawmakers are nearing a high-stakes decision that will decide the fate of a climate initiative that Gov. Jerry Brown holds up as a model to be replicated around the world to confront rising global temperatures.

The vote Monday on whether to give another decade of life to California’s cap-and-trade program has global implications as the largest U.S. state moves to be a leader in reducing carbon emissions at a time when President Donald Trump is pulling...